Parkinson's disease (PD) is a neurological condition, which affects the brain. PD gets worse over time, but how quickly it progresses varies a lot from person to person. Some symptoms of PD are tremors, stiffness, and slowness of movement. This study measures the efficacy, safety, and tolerability of ABBV-951 versus oral Levodopa (LD)/Carbidopa (CD) [LD/CD] in advanced PD participants to achieve reduction in motor fluctuations. ABBV-951 is an investigational (unapproved) drug containing Levodopa Phosphate/Carbidopa Phosphate (LDP/CDP) given subcutaneously (under the skin) for the treatment of Parkinson's Disease. The study has two treatment arms . In one arm, participants will be given ABBV-951 plus oral placebo (does not contain treatment drug). In the second arm, participants will be given placebo solution and LD/CD tablets. Adult participants with advanced PD will be enrolled. Approximately 130 participants will be enrolled in the study in approximately 80 sites across the world. In one arm, participants will receive ABBV-951 solution as a continuous infusion under the skin plus oral placebo capsules for LD/CD. In the second arm, participants will receive placebo solution for ABBV-951 as a continuous infusion under the skin plus oral capsules containing LD/CD tablets. The treatment duration is 12 weeks. There may be higher treatment burden for participants in this trial compared to their standard of care. Participants will attend regular visits during the course of the study at a hospital or clinic. The effect of the treatment will be checked by medical assessments, blood tests, checking for side effects, and completing questionnaires.



Eligible Ages
Over 30 Years
Eligible Genders
Accepts Healthy Volunteers

Inclusion Criteria

  • Diagnosis of idiopathic Parkinson's Disease (PD) that is levodopa-responsive. - Participants must be taking a minimum of 400 milligrams/day (mg/day) of Levodopa (LD) equivalents and be judged by the investigator to have motor symptoms inadequately controlled by current therapy, have a recognizable/identifiable "Off" and "On" states (motor fluctuations), and have an average "Off" time of at least 2.5 hours/day over 3 consecutive PD Diary days with a minimum of 2 hours each day. - Participant or caregiver, if applicable, demonstrates the understanding and correct use of the delivery system, including the insertion of the cannula into the participant's abdomen, as assessed by the investigator or designee during the Screening period.

Exclusion Criteria

  • Clinically significant, unstable medical conditions or any other reason that the investigator determines would interfere with the participant's participation in this study or would make the participant an unsuitable candidate to receive study drug. - History of allergic reaction or significant sensitivity to LD or constituents of the study drug (and its excipients) and/or other products in the same class. - Has no known active Coronavirus Disease - 2019 (COVID-19) infection.

Study Design

Phase 3
Study Type
Intervention Model
Parallel Assignment
Primary Purpose
Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)

Arm Groups

ArmDescriptionAssigned Intervention
ABBV-951 + Placebo for Levodopa/Carbidopa (LD/CD)
Participants will receive ABBV-951 by continuous subcutaneous infusion (CSCI) and oral placebo for LD/CD for 12 weeks
  • Drug: ABBV-951
    Solution for continuous subcutaneous infusion (CSCI)
  • Drug: Placebo for Levodopa/Carbidopa (LD/CD)
    Oral capsule
Active Comparator
Levodopa/Carbidopa (LD/CD) + Placebo for ABBV-951
Participants will receive oral LD/CD and CSCI of placebo for ABBV-951 for 12 weeks
  • Drug: Levodopa/Carbidopa (LD/CD)
    Oral encapsulated tablet
  • Drug: Placebo for ABBV-951
    Solution for continuous subcutaneous infusion (CSCI)

Recruiting Locations

University of Alabama at Birmingham - Main /ID# 216595
Birmingham, Alabama 35233

University of South Alabama /ID# 216757
Mobile, Alabama 36604-3302

Xenoscience, Inc /ID# 217110
Phoenix, Arizona 85004

St Joseph's Hospital& Medical Center-Barrow Neurological Institute /ID# 216566
Phoenix, Arizona 85013-4407

Movement Disorders Center of Arizona /ID# 216503
Scottsdale, Arizona 85258-4582

Banner Sun Health Res Inst /ID# 216507
Sun City, Arizona 85351

University of Arkansas for Medical Sciences /ID# 216501
Little Rock, Arkansas 72205

Parkinson's and Movement /ID# 216705
Fountain Valley, California 92708

Neuro Pain Medical Center /ID# 216551
Fresno, California 93710-5473

University of California, San /ID# 216598
La Jolla, California 92093

Loma Linda University Medical /ID# 216500
Loma Linda, California 92354

Collaborative Neuroscience Net /ID# 216970
Long Beach, California 90806

University of California, Los Angeles /ID# 216674
Los Angeles, California 90095

SC3 Research Group - Pasadena /ID# 216821
Pasadena, California 91105-3149

Cedars-Sinai Medical Center - West Hollywood /ID# 216561
West Hollywood, California 90048

University of Colorado Hosp /ID# 216527
Aurora, Colorado 80045

Alpine Clinical Research Center /ID# 216637
Boulder, Colorado 80301-1880

Denver Neurological Research, LLC /ID# 216784
Denver, Colorado 80210-7009

Rocky Mountain Movement Disorders Center /ID# 216737
Englewood, Colorado 80113-2736

Christiana Care Health Service /ID# 216515
Newark, Delaware 19713

Georgetown University Hospital /ID# 216632
Washington, District of Columbia 20007

Brain Matters Research /ID# 217089
Delray Beach, Florida 33445

Fixel Institute for Neurological Diseases /ID# 216514
Gainesville, Florida 32608-3928

Visionary Investigators Network - Miami /ID# 216679
Miami, Florida 33176-2148

Renstar Medical Research /ID# 216765
Ocala, Florida 34470

Neurology Associates Ormond Beach /ID# 216521
Ormond Beach, Florida 32174

Parkinson's Disease Treatment Center of Southwest Florida /ID# 222656
Port Charlotte, Florida 33980

University of South Florida /ID# 216638
Tampa, Florida 33612

Premiere Research Institute at Palm Beach Neurology /ID# 217207
West Palm Beach, Florida 33407-3209

The Neurological Center of North Georgia /ID# 216499
Gainesville, Georgia 30501

Rush University Medical Center /ID# 216567
Chicago, Illinois 60612

University of Chicago Medical /ID# 217187
Chicago, Illinois 60637

Indiana Clinical Research Cent /ID# 216615
Indianapolis, Indiana 46202

Univ Kansas Med Ctr /ID# 216528
Kansas City, Kansas 66160

St Elizabeth's Medical Center - Brighton /ID# 216716
Brighton, Massachusetts 02135-2907

Michigan State University /ID# 217158
East Lansing, Michigan 48824

Clinical Research Professionals - Chesterfield /ID# 216669
Chesterfield, Missouri 63005-1205

St. Luke's Hosp. of Kansas Cit /ID# 216633
Kansas City, Missouri 64111

Washington University-School of Medicine /ID# 216548
Saint Louis, Missouri 63110

Global Neurosciences Institute /ID# 217875
Lawrenceville, New Jersey 08648-2300

Northwell Health /ID# 216833
Lake Success, New York 11042

Mount Sinai Beth Israel /ID# 216712
New York, New York 10003

University of Rochester /ID# 218737
Rochester, New York 14642-0001

Wake Forest Univ HS /ID# 216522
Winston-Salem, North Carolina 27157

Ohio State University - Wexner Medical Center /ID# 216900
Columbus, Ohio 43210-1229

The Orthopedic Foundation /ID# 217157
New Albany, Ohio 43054-8167

The Movement Disorder Clinic of Oklahoma /ID# 216860
Tulsa, Oklahoma 74136-6378

Legacy Research Institute /ID# 216558
Portland, Oregon 97232-2003

University of Pennsylvania /ID# 216560
Philadelphia, Pennsylvania 19104-5502

Thomas Jefferson University Hospital /ID# 216553
Philadelphia, Pennsylvania 19107

Prisma Health /ID# 216594
Greenville, South Carolina 29615-3593

Premier Neurology, P.C. /ID# 217308
Greer, South Carolina 29650

Coastal Neurology /ID# 217190
Port Royal, South Carolina 29935-2029

KCA Neurology - Franklin /ID# 217419
Franklin, Tennessee 37067-5914

Vanderbilt Univ Med Ctr /ID# 216675
Nashville, Tennessee 37232-0011

Houston Pulmonary Sleep and Allergy Associates /ID# 216942
Cypress, Texas 77429

Kerwin Research Center /ID# 216587
Dallas, Texas 75231-4316

Neurology Consultants of Dallas - LBJ Fwy /ID# 216564
Dallas, Texas 75243-1188

Texas Movement Disorder Specialist /ID# 216523
Georgetown, Texas 78628-4126

Houston Methodist Hospital /ID# 216707
Houston, Texas 77030

Central Texas Neurology Consul /ID# 216629
Round Rock, Texas 78681

University of Utah Health Care /ID# 216710
Salt Lake City, Utah 84132

Meridian Clinical Research /ID# 216731
Norfolk, Virginia 23502-3932

Neurological Associates - Forest Ave /ID# 216636
Richmond, Virginia 23229-4913

Swedish Neuroscience /ID# 216526
Seattle, Washington 98122-5788

Inland Northwest Research /ID# 221036
Spokane, Washington 99202-1342

Medical College of Wisconsin /ID# 216498
Milwaukee, Wisconsin 53226-3522

More Details


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Study information shown on this site is derived from ClinicalTrials.gov (a public registry operated by the National Institutes of Health). The listing of studies provided is not certain to be all studies for which you might be eligible. Furthermore, study eligibility requirements can be difficult to understand and may change over time, so it is wise to speak with your medical care provider and individual research study teams when making decisions related to participation.